1. Field of the Invention
The invention relates to semiconductor processing and more specifically to high resolution lithographic processes using soft x-rays or ion beams.
2. Description of the Prior Art
One of the fundamental limitations of high density in semiconductor circuits has been the resolution of the litographic processes. Techniques currently offering the most promise of improving the resolution of lithography is either the so called electron beam writing, processes using flood beams of short wavelength radiation such as x-rays or flood beams of ions. Electron beam writing while providing high resolution is a relatively low production technique due to the time required for the beam writing process. X-ray and flood ion beam lithography has been difficult because the masks are fragile due to the fact that the preferred mask is a thin metal foil such as beryllium. In addition to the fragile nature of such mask, alignment has been difficult due to the fact that a preferred alignment technique is an optical process (i.e., using visible light) and the metallic foil mask is non-transparent in the visible range.